New design and seismic retrofit applications of fluid viscous-damped bracing systems

A dissipative bracing system incorporating pressurized fluid viscous spring-dampers as passive protective devices has been conceived and studied for many years by the authors, also within European Commission-funded and Italian National Research Projects. As a concluding stage of this activity, a set of demonstrative case studies was examined, so as to illustrate the improvement of seismic performance guaranteed by the system in realistic and actual design applications, as well as to further develop the technical implementation procedures and details needed for its practical installation in new and existing buildings. This paper offers a selection of three among these case studies, and namely a steel school building and a reinforced concrete school building as retrofit interventions, and a lightweight steel fitness centre as a new structure. The mechanical parameters, dimensions, layouts and locations selected for the constituting elements of the system, and a synthesis of the design and performance evaluation analyses carried out, all developed according to a full non-linear dynamic approach, are presented. The results of the analyses show a remarkable improvement of seismic response capacities in the two retrofit problems, which allows reaching the high performance levels postulated for these interventions. Concerning the new steel fitness centre, the protective technology produces a drastic drop in member sections, with a considerably lower impact on the visual perception of the building and an approximate 50% cut in the cost of the steel structure (spring-dampers excluded), as compared to a traditional bracing solution designed for the same performance objectives.